With touch-sensitive displays on small client devices such as a Smart Phone or tablet computer, the size of the display poses some difficulties for the user. Even if the user's eyesight is good, it is difficult to manipulate graphical controls with a finger that is large relative to the screen or to the displayed graphical controls. In many instances, a user must zoom in (e.g., by “pinching”), interact with the control, then zoom back out to see the effect of the change. This is particularly cumbersome when the process of zooming in and out must be repeated multiple times.
A similar problem occurs on a larger display screen when the user has physical limitations. For example, a user with impaired eyesight may have difficulty interacting with an ordinary graphical control. Alternatively, even a person with good eyesight may have impaired motor skills, making it difficult to accurately manipulate a pointing device (e.g., a mouse) or to position a finger accurately over a graphical control. The problems created by impaired eyesight or impaired motor skills are similar to the problems created by having a display screen that is small.